This study evaluates the effect of improved sweet potato varieties on household food security. Data was collected from cross sectional survey of 164 sweet potato farmers in Kenya. Food security was measured using the Household Dietary diversity Score (HDDS) and endogenous switching probit model used to assess the effect of improved sweet potato varieties on household food security. Off-farm income, output of sweet potato, farm size, land tenure and government extension were the main drivers of food security. Findings were that adopters of improved varieties were likely to be food secure compared to their counterfactual case of not adopting the improved varieties. Additionally, non adopters would do no better or worse than a random individual if they adopt the improved sweet potato varieties. Policies that increase improved sweet potato variety productivity and ease farmers’ adoption constraints can ensure that farmers diversify farm income to enhance the food security of households